Hybrid electric vehicles (HEV's) employ both an internal combustion engine and an electric machine that can be used either individually or in combination to propel the vehicle. A variety of different powertrains may be utilized by HEV's. One type of powertrain is referred to as a modular hybrid transmission (MHT). MHT's include a parallel configuration in which the engine is connected to the electric machine by a disconnect clutch and the electric machine drives a torque converter input of a transmission. The transmission has an output connected to a differential that is coupled to the drive wheels of the vehicle.
The engine may be started independently of the electric machine in a MHT. Once the engine is up to speed, the disconnect clutch may be commanded to engage to allow the engine to deliver torque to the transmission. Timing the engagement of the disconnect clutch is important for start performance of the engine.